1. Field of the Invention
The present invention relates to an optical disk player, and more particularly to an apparatus and method for controlling a tracking balance of an optical disk player which automatically controls a tracking error due to installing positions of a disk, a photo diode, a laser diode, and an object lens.
2. Description of the Prior Art
Data recording/reproducing apparatuses using optical disks such as a laser disk and a compact disk have been commercially available in recent years. In the compact disk, a signal is recorded on a track arranged helical in a direction from an inner side toward an outer side, of which the distance between adjacent tracks, i.e., track pitch of a high density, is about 1.6 .mu.m. In order to record or read out data from the optical disk, a laser beam is irradiated onto a data recording track and the quantity of the light reflected from the disk is converted into an electric signal, thereby reading the data. When the tracks are helical formed on the optical disk, since the sectors of a single track are not equidistant from the center of the rotation of the disk due to an eccentricity on the disk, tracking control is necessary in the read mode to accurately irradiate the track with a laser beam. Even if the tracks are concentrically formed, sectors of a single track are not equidistant from the center of the rotation of the disk due to the eccentricity in the disk, and therefore, tracking control is essential. It is necessary to control the position of the laser beam to be incident on the track of turning disk.
On the other hand, a motor for turning a compact disk causes a phenomenon that moves the track inwardly and outwardly at the time of turning, and therefore the pick-up follows this and a device controls positioning on a proper track which is called a tracking servo. A servo error signal for indicating how much deviation from an optimum state occurred is required for all servos. The compact disk player applies various optical methods to produce the servo error. This tracking control has been conventionally performed by a one beam method using a single laser beam or a three beam method wherein the single laser beam is separated into three beams. The three beam method is more often used because it is more stable for the tilting of a disk or the defect of a disk than the one beam method. One example of this three beam tracking method is disclosed in U.S. Pat. No. 5,128,914.
However, during the process to perform the tracking servo by using the three beam system, it is difficult to accurately correct the tracking servo when the tracking servo is unbalanced during the turning of the optical disk because the tracking error caused by the lens is fixed value at the time to make the tracking servo.